Email Migration

How to Fix Microsoft 365 Not Receiving Emails After Migration

Maira Mehtab Sep 20, 2026 869 views

Question details

The user migrated their email from a server to Microsoft 365 and linked it with a personal Gmail account, but Microsoft 365 is unable to receive most incoming messages, with only one address working.

Product: Microsoft 365
Device & OS: not provided
Scenario: Setting up and routing incoming emails following a server migration to Microsoft 365.
Observed behavior: Microsoft 365 fails to receive incoming emails for most addresses post-migration, though one address successfully receives messages.

Before you start

Before troubleshooting, try sending a test email from an external account (like a personal Gmail or Yahoo account) to the affected Microsoft 365 address and note if you receive a Non-Delivery Report (NDR) bounce-back message.

Solution 1

Identify Account Type and Test Outlook Platforms

Determine your exact Microsoft 365 subscription type and test both the web and desktop applications to isolate where the delivery failure occurs.

Email syncing issues can sometimes be localized to the desktop application rather than the server itself. Verifying your account type and checking Outlook on the web helps narrow down the problem.

Confirm Account Type

Verify if your Microsoft 365 account is a Business, Education, Personal, or Custom Domain account, as this dictates how your mail servers should be configured.

Test Outlook on the Web

Log in to Outlook.com or the Microsoft 365 web portal using a browser to check if incoming emails are arriving on the server but failing to sync to your desktop.

Check Outlook Desktop Sync

Open the Outlook desktop application, navigate to the 'Send / Receive' tab, and click 'Update Folder' to manually force synchronization.

Analyze Non-Delivery Reports

Review any Non-Delivery Reports (NDRs) sent back to the original sender's inbox, as these error codes will explicitly state why the Microsoft 365 server rejected the email.

Solution 2Recommended

Verify MX Records and Custom Domain Settings

Check your domain's DNS records and mail routing settings, which are the most common culprits for missing emails after a migration.

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Frequently Asked Questions

Why is only one email address receiving messages after migrating to Microsoft 365?

This typically occurs if the primary domain's MX records are correct, but secondary alias addresses, subdomains, or specific internal relay settings for individual user accounts were not fully configured or verified in the Exchange Admin Center during the migration.

How long does it take for MX records to update after a migration?

DNS changes, including MX records, can take anywhere from a few minutes to 48 hours to fully propagate across the internet. During this propagation window, emails may still mistakenly route to your old mail server.

What is a Non-Delivery Report (NDR) in Microsoft 365?

An NDR is an automated bounce message returned to the sender when an email cannot be delivered. It contains diagnostic error codes that explain why the delivery failed, such as 'User Unknown', 'Mailbox Full', or specific DNS routing failures.

Can linking a personal Gmail account block my Microsoft 365 emails?

Yes, if connected accounts or forwarding rules are incorrectly configured within Outlook, incoming emails might be automatically forwarded, moved to different folders, or rejected. Check your Outlook mailbox rules and forwarding settings to ensure messages are staying in your primary inbox.

Migration & Recovery